A computer bus (or simply “bus”) is a collection of wires over which data is transmitted between devices, such as a processor and a memory. Data is transferred over a bus in a specific format. For example, the data may be transferred in “frames”. Generally speaking, a frame is a data structure that organizes data packets into time slots that specify the order in which the data packets are to be transferred. Other information may also be included in a frame, such as the port(s) to which data packets are to be transferred.
A framer is a device that receives data packets from a source and that forms frames from the data packets. The framer typically stores the frames in a buffer memory and transmits data packets from the buffer memory onto a bus at the appropriate time slots specified in the frame.